PolygonMesh.cc

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#include <esg/mesh/PolygonMesh.h>

using namespace esg;

PolygonMesh::PolygonMesh(const Vertex3   val[],
                         const unsigned  index[],
                         int             nVert,
                         const Vertex3   normals[],
                         const unsigned  nindex[],
                         const Vector3&  normal,
                         float           dr)
{
    Vert  *V1, *V2, *V;
    Plane *F;
    Edge  *E;

    if (nVert == 0) {
        fprintf(stderr,"PolygonMesh Error: Polygon without vertices\n");
        return;
    }

    F = MF(normal.x, normal.y, normal.z, -dr);
    V1 = MV(val[index[0]].x, val[index[0]].y, val[index[0]].z);
    if (normals && nindex)  // set vertex normal if any
        V1->normal.set(normals[nindex[0]]);
    else
        V1->normal.set(normal);
    pSolid = MVSF(F,V1);
    V = V1; // store first vertex

    for (register int i = 1; i < nVert; i++) {
        V2 = MV(val[index[i%nVert]].x,
                val[index[i%nVert]].y,
                val[index[i%nVert]].z);
        if (normals && nindex)   // set vertex normal if any
            V2->normal.set(normals[nindex[0]]);
        MEV(pSolid, V1, V2, &E, F);
        V1 = V2;
    }
    MEF(pSolid, V1, V, F, F, &E);
}


Mesh::Solid* PolygonMesh::cut(float ar, float br, float cr, float dr)
{
  int pozit, negat;
  Solid* pRet;

  if (!pSolid) return NULL;
  Vertex_Plane_position(*pSolid, ar, br, cr, dr, pozit, negat);
  if (pozit == 0) return NULL;
  if (negat == 0) {
    pRet = pSolid;
    pSolid = NULL;
    return pRet;
  }

  pRet = new Solid;
  Copy_solid(pSolid, pRet);

  Edge* pEdgeA = pSolid->first_edge;
  Edge* pEdgeB = pRet->first_edge;
  Edge* pTmp;
  Vert* pNewV;
  Edge* pNewE;

  do {  // Add points of intersection to polygon
    if (pEdgeA->V2->fxyz < 0) {
      if (pEdgeA->V1->fxyz > 0) {
        pNewV = Vertex_of_cut(pEdgeA->V1, pEdgeA->V2);
        SEMV(pSolid, pEdgeA, pNewV, &pNewE);
        pEdgeA = pNewE;
        pNewV = Vertex_of_cut(pEdgeB->V1, pEdgeB->V2);
        SEMV(pRet, pEdgeB, pNewV, &pNewE);
        pEdgeB = pNewE;
      }
    }
    else if (pEdgeA->V2->fxyz > 0) { 
      if (pEdgeA->V1->fxyz < 0) {
        pNewV = Vertex_of_cut(pEdgeA->V1, pEdgeA->V2);
        SEMV(pSolid, pEdgeA, pNewV, &pNewE);
        pEdgeA = pNewE;
        pNewV = Vertex_of_cut(pEdgeB->V1, pEdgeB->V2);
        SEMV(pRet, pEdgeB, pNewV, &pNewE);
        pEdgeB = pNewE;
      }
    }
    
    pEdgeA = pEdgeA->next_edge;
    pEdgeB = pEdgeB->next_edge;
  } while (pEdgeA != pSolid->first_edge);

  pEdgeA = pSolid->first_edge;
  pEdgeB = pRet->first_edge;

  do { // Delete edges outside (inside) half-space
    if (pEdgeA->V1->fxyz >= 0 && pEdgeA->V2->fxyz >= 0) {
      pTmp = pEdgeA->next_edge;
      DeleteEdge(pSolid, pEdgeA);
      pEdgeA = pTmp;
    }
    else pEdgeA = pEdgeA->next_edge;
    
    if (pEdgeB->V1->fxyz <= 0 && pEdgeB->V2->fxyz <= 0) {
      pTmp = pEdgeB->next_edge;
      DeleteEdge(pRet, pEdgeB);
      pEdgeB = pTmp;
    }
    else pEdgeB = pEdgeB->next_edge;
  } while (pEdgeA != pSolid->first_edge);

  return pRet;
}

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